兄弟连区块链教程Fabric1.0源代码分析scc（系统链码）cscc（通道相关），2018年下半年，区块链行业正逐渐褪去发展之初的浮躁、回归理性，表面上看相关人才需求与身价似乎正在回落。但事实上，正是初期泡沫的渐退，让人们更多的关注点放在了区块链真正的技术之上。

# Fabric 1.0源代码笔记 之 scc（系统链码） #cscc（通道相关）

## 1、cscc概述

cscc代码在core/scc/cscc/configure.go。

## 2、PeerConfiger结构体

```go

type PeerConfiger struct {

    policyChecker policy.PolicyChecker

}

//代码在core/scc/cscc/configure.go

```

## 3、Init方法

```go

func (e *PeerConfiger) Init(stub shim.ChaincodeStubInterface) pb.Response {

    //初始化策略检查器，用于访问控制

    e.policyChecker = policy.NewPolicyChecker(

        peer.NewChannelPolicyManagerGetter(),

        mgmt.GetLocalMSP(),

        mgmt.NewLocalMSPPrincipalGetter(),

    )

    return shim.Success(nil)

}

//代码在core/scc/cscc/configure.go

```

## 4、Invoke方法

```go

func (e *PeerConfiger) Invoke(stub shim.ChaincodeStubInterface) pb.Response {

    //args[0]为JoinChain或GetChannels

    args := stub.GetArgs()

    fname := string(args[0]) //Invoke function

    sp, err := stub.GetSignedProposal() //获取SignedProposal

    switch fname {

    case JoinChain: //加入通道

        //此处args[1]为创世区块

        block, err := utils.GetBlockFromBlockBytes(args[1])

        cid, err := utils.GetChainIDFromBlock(block)

        err := validateConfigBlock(block)

        err = e.policyChecker.CheckPolicyNoChannel(mgmt.Admins, sp)

        return joinChain(cid, block)

    case GetConfigBlock:

        err = e.policyChecker.CheckPolicy(string(args[1]), policies.ChannelApplicationReaders, sp)

        return getConfigBlock(args[1])

    case GetChannels:

        err = e.policyChecker.CheckPolicyNoChannel(mgmt.Members, sp)

        return getChannels()

    }

}

//代码在core/scc/cscc/configure.go

```

## 5、其他方法

```go

//校验创世区块

func validateConfigBlock(block *common.Block) error

func joinChain(chainID string, block *common.Block) pb.Response

func getConfigBlock(chainID []byte) pb.Response

func getChannels() pb.Response

//代码在core/scc/cscc/configure.go

```

### 5.1、joinChain

```go

func joinChain(chainID string, block *common.Block) pb.Response {

    err := peer.CreateChainFromBlock(block) //创建chain

    peer.InitChain(chainID)

    err := producer.SendProducerBlockEvent(block)

    return shim.Success(nil)

}

//代码在core/scc/cscc/configure.go

```

#### 5.1.1、创建Chain（或channel）

peer.CreateChainFromBlock(block)代码如下：

```go

func CreateChainFromBlock(cb *common.Block) error {

    cid, err := utils.GetChainIDFromBlock(cb) //获取ChainID

    var l ledger.PeerLedger

    l, err = ledgermgmt.CreateLedger(cb) //创建Ledger

    return createChain(cid, l, cb)

}

//代码在core/peer/peer.go

```

createChain(cid, l, cb)代码如下：

```go

func createChain(cid string, ledger ledger.PeerLedger, cb *common.Block) error {

    envelopeConfig, err := utils.ExtractEnvelope(cb, 0) //获取配置Envelope

    configtxInitializer := configtx.NewInitializer() //type initializer struct

    gossipEventer := service.GetGossipService().NewConfigEventer() //获取gossipServiceInstance

    gossipCallbackWrapper := func(cm configtxapi.Manager) {

        ac, ok := configtxInitializer.ApplicationConfig()

        if !ok {

            // TODO, handle a missing ApplicationConfig more gracefully

            ac = nil

        }

        gossipEventer.ProcessConfigUpdate(&chainSupport{

            Manager:     cm,

            Application: ac,

        })

        service.GetGossipService().SuspectPeers(func(identity api.PeerIdentityType) bool {

            // TODO: this is a place-holder that would somehow make the MSP layer suspect

            // that a given certificate is revoked, or its intermediate CA is revoked.

            // In the meantime, before we have such an ability, we return true in order

            // to suspect ALL identities in order to validate all of them.

            return true

        })

    }

    trustedRootsCallbackWrapper := func(cm configtxapi.Manager) {

        updateTrustedRoots(cm)

    }

    configtxManager, err := configtx.NewManagerImpl(

        envelopeConfig,

        configtxInitializer,

        []func(cm configtxapi.Manager){gossipCallbackWrapper, trustedRootsCallbackWrapper},

    )

    if err != nil {

        return err

    }

    // TODO remove once all references to mspmgmt are gone from peer code

    mspmgmt.XXXSetMSPManager(cid, configtxManager.MSPManager())

    ac, ok := configtxInitializer.ApplicationConfig()

    if !ok {

        ac = nil

    }

    cs := &chainSupport{

        Manager:     configtxManager,

        Application: ac, // TODO, refactor as this is accessible through Manager

        ledger:      ledger,

    }

    c := committer.NewLedgerCommitterReactive(ledger, txvalidator.NewTxValidator(cs), func(block *common.Block) error {

        chainID, err := utils.GetChainIDFromBlock(block)

        if err != nil {

            return err

        }

        return SetCurrConfigBlock(block, chainID)

    })

    ordererAddresses := configtxManager.ChannelConfig().OrdererAddresses()

    if len(ordererAddresses) == 0 {

        return errors.New("No ordering service endpoint provided in configuration block")

    }

    service.GetGossipService().InitializeChannel(cs.ChainID(), c, ordererAddresses)

    chains.Lock()

    defer chains.Unlock()

    chains.list[cid] = &chain{

        cs:        cs,

        cb:        cb,

        committer: c,

    }

    return nil

}

//代码在core/peer/peer.go

```

补充initializer：

```go

type initializer struct {

    *resources

    ppr *policyProposerRoot

}

//代码在common/configtx/initializer.go

```

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